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Altera_Forum's avatar
Altera_Forum
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20 years ago

How to tell there is data from UART?

Hi

Browsing through Altera documentation suggests I should be using the HAL with a UART.

So using the HAL how do I determine if there is data available from the UART before calling getchar()? I need my system to be doing other stuff and can't have it block while waiting for the UART to receive data. I can see I have to use the fast version of the driver so that the UART operates under interrupts but I can't see an equivalent to the old kbhit() function.

Ta,

Mike

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    Just an idea, can you fiddle with the driver to be able to look at the pointers for the receive buffer? Maybe you can work out a function like kbhit then.

    Stefaan
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    open device uart in non blocking mode:

    static int fdterm; // FILEDESCRIPTOR RETURNED BY OPEN

    ..

    fdterm = open("/dev/uart1", O_RDWR | O_NONBLOCK | O_NOCTTY);

    ..

    reading is done by

    ..

    res=read(fdterm,uart1_tempbuff,sizeof(uart1_tempbuff)-1);

    if(res>0) {

    ... we have received some bytes

    }
  • Altera_Forum's avatar
    Altera_Forum
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    20 years ago

    Fischer

    Thanks for your reply.

    I managed to work it out for myself but it is nice to have confirmation from a expert that I am doing the right thing.

    Mike